1w5r
From Proteopedia
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X-RAY CRYSTALLOGRAPHIC STRCUTURE OF A C70Q MYCOBACTERIUM SMEGMATIS N-ARYLAMINE ACETYLTRANSFERASE
Overview
The NATs (arylamine N-acetyltransferases) are a well documented family of, enzymes found in both prokaryotes and eukaryotes. NATs are responsible for, the acetylation of a range of arylamine, arylhydrazine and hydrazine, compounds. We present here an investigation into the catalytic triad of, residues (Cys-His-Asp) and other structural features of NATs using a, variety of methods, including site-directed mutagenesis, X-ray, crystallography and bioinformatics analysis, in order to investigate, whether each of the residues of the catalytic triad is essential for, catalytic activity. The catalytic triad of residues, Cys-His-Asp, is a, well defined motif present in several families of enzymes. We mutated each, of the catalytic residues in turn to investigate the role they play in, catalysis. We also mutated a key residue, Gly126, implicated in acetyl-CoA, binding, to examine the effects on acetylation activity. In addition, we, have solved the structure of a C70Q mutant of Mycobacterium smegmatis NAT, to a resolution of 1.45 A (where 1 A=0.1 nm). This structure confirms that, the mutated protein is correctly folded, and provides a structural model, for an acetylated NAT intermediate. Our bioinformatics investigation, analysed the extent of sequence conservation between all eukaryotic and, prokaryotic NAT enzymes for which sequence data are available. This, revealed several new sequences, not yet reported, of NAT paralogues., Together, these studies have provided insight into the fundamental core of, NAT enzymes, and the regions where sequence differences account for the, functional diversity of this family. We have confirmed that each of the, three residues of the triad is essential for acetylation activity.
About this Structure
1W5R is a Single protein structure of sequence from Mycobacterium smegmatis. Active as Arylamine N-acetyltransferase, with EC number 2.3.1.5 Full crystallographic information is available from OCA.
Reference
Investigation of the catalytic triad of arylamine N-acetyltransferases: essential residues required for acetyl transfer to arylamines., Sandy J, Mushtaq A, Holton SJ, Schartau P, Noble ME, Sim E, Biochem J. 2005 Aug 15;390(Pt 1):115-23. PMID:15869465
Page seeded by OCA on Wed Nov 21 05:14:25 2007
